Oil cracking still



Jan. 12, 1932. H w|DDELL 1,841,072

011. cimcxme STILL Filed Aug. 14, 1926 Patented Jan. 12, 1932 HENRY E.WIDDELL, OF KANSAS CITY, MISSOURI OIL CRACKING STILL Application filedAugust 14, 1926. Serial No. 129,170.

This invention relates to heating apparatus and method, and moreparticularly to heaters for fluid such as are used in oil crackingstills.

An object of this invention is to increase the thermal efliciency ofheater for fluids.

Another object is to provide means for controlling the temperature ofgases in a heater without wasting the heat developed.

Another object is to protect the walls of the heating apparatus fromexcessive heat.

Another object is to provide means for utilizing the radiant heatgenerated upon combustion of fuel.

Another object is to provide an improved method of controlling thetemperature of combustion gases and conserving the heat developed.

Other objects will hereinafter appear.

In the present common practice, oils are cracked by being heated inoil-fired stills. If the oil fuel is eificiently burned with a properexcess of air (about 50%) the temperature of the gases will be about3500 F. In certain instances it is desirable that the gases ofcombustion which contact with the container holding the oil to becracked shall. be approximately from 1300 F'. to 1600 F. In Jrder toreduce the gases to the desired temperature, large quantities of air inexcess of zhat required for combustion (generally from 200 to 250%) areadmitted and absorb much )f the heat developed by the fuel. The vol-.inie of stack gases is, of course, large and .he heat contentrepresents approximately of he fuel burned.

I prop se to provide means for absorbing ieat from the burning gases insuch man- 181 that it may perform some useful purpose ind at the sametime reduce the temperature )f the gases to a desired point without theLdII'llSSlOIl of more air than is necessary to nsure completecombustion. The gases proluce during combustion, a temperature of .bout3500 F. and can be cooled to between 400 F. and 1600 F. while containingonly bout %excess of air. The volume of tack gases is small and theirheat content epregents only about 13% of the fuel conume A convenientmanner of absorbing the heat is to expose to it some fluid, which may bea liquid, vapor, gas or mixture of any or all of these, other than theoil being cracked. The fluid should not only be capable of absorbingheat, but should be such that it being heated will produce some usefulresult. Examples of such fluids are oils or water which it is desired toheat or vaporize, or steam to be superheated.

The invention will be better understood from the description of onepractical apparatus, in which it is embodied and by which it may bepracticed, illustrated in the accompanying drawings, in which Fig. l isa longitudinal section of the apparatus;

Fig. 2 is a transverse section taken on line 11I1 of Fig. 1; and

Fig. 3 is a plan section taken on line IIIIH of Fig. 1.

The furnace comprises a top 1, sides 2 and 3, and ends 4 and 5 of asuitable refractory material, such as fire brick. The interior space isdivided into two compartments 6 and 7 by a bridge wall 8 which extendwell up toward the top. Compartment 6 is preferably considerably largerthan compartment 7.

In compartment 6, hereinafter referred to as the combustion chamber, areburners 9 b which a fuel, such as oil, may be introduced.

Compartment 7, hereinafter called the cracking chamber, communicateswith a flue 10 through which the burned gases may escape after passingthrough both chambers.

Within the combustion chamber are a series of tubes 11 supported by andclose to the walls of the chamber. These tubes are so connected a fluidmay circulate'therethrough in a continuous circuitous and upward pathfrom the inlet pipe and valve 12 to the transfer pipe 13.

The transfer pipe communicates with a series of tubes 14 supported byand close beneath the top of the furnace and co-extensive therewith.Fluid may travel continuously upward and back through these tubes untilit reaches discharge pipe and valve 15.

The above described tubes are for the circulation of the cooling fluid,not of the oil to be cracked.

In'the cracking chamber is a bank of tubes 16, having an inlet pipe andvalve 17 through which oil to be cracked may be introduced and an outletand valve 18 through which this oil is discharged.

By arranging the cooling-fluid tubes as shown, the tubes are supportedon the walls and top. They are positioned toshield and draw heat fromthese surfaces and thus reduce their temperature, thus reducing the heatwhich would otherwise radiate from the furnace and at the same timelengthen the life of the walls. They absorb the radiant heat generatedby the burning fuel. They are out of the path of the hot gases and donot absorb heat from these by convection but permit this to be deliveredto the cracking tubes.

The cooling-fluid is one which it is desired to heat so that the heatabsorbed is not wasted while the temperature at the cracking chamber iskept down to any desired point.

While I have described the illustrated embodiment of my invention withsome particularity, obviously many others will readily occur to thoseskilled in this art and I do not therefore limit myself to the precisedetails shown, but claim as my invention all embodiments coming Withinthe scope of the appended claim.

What I claim is:

The method of controlling the temperature in an oil cracking furnacewhich comprises burning fuel in the furnace with small excess of air andpassing a heat-absorbing fluid through passages adjacent the wallsthereof at a rate to absorb sufiicient heat to reduce the gases to thedesired temperature, and exposing the oil to be cracked only to thecooled gases.

In testimony whereof I hereunto aflix my signature this 9th day ofAugust, 1926 HENRY E. WIDDELL.

